Subtracting decimals

In this lesson, we will learn:

• How to subtract decimal numbers using base ten (block) models
• That subtracting decimal numbers is the same as subtracting whole numbers, which involves lining up the right place values and exchanging

Notes:

• To subtract decimals with base ten (block) models:
• Remember the three types of blocks used to represent the ones, tenths, and hundredths place values
• "One whole" or hundred block = ones place value
• Column (stick or rod) = tenths place value
• Single square = hundredths place value

• A subtraction statement is made of: minuend - subtrahend = difference
• Cross out the blocks that you are subtracting (subtrahend from the minuend), until you've crossed out all matching pairs (subtrahend all crossed out).
• Exchange (or "borrow") from a bigger block if you don't have enough blocks to cross out. One big block can be split into 10 of the next smaller type of block (next place value).

• To subtract decimals, line up the decimal point to make sure you are adding the right place values in the same columns. Exchange (borrow) whenever necessary.
• Sometimes, you will have to write one or more extra zeroes to a number after the decimal point (trailing zeroes) when the minuend/subtrahend don't have the same number of place values.